Ἡρακλείδης ὁ Ποντικός
Heraclides of Pontus (387-312 BC) was a Greek philosopher famous for being one of the first to propose that the Earth revolves on its own axis.
Little is known of Heraclides' life and work. Although he is often mentioned in other works, is own works do not survive other than as quotations in later writings, and lists of titles of works he is said to have composed. We do know that he lived and died in the town of Heraclea Pontica, which is now the town of Karadeniz Ereğli in Turkey, and he does seem to have been an extremely prolific writer on all manner of topics ranging among mathematics, astronomy, music, grammar, physics, history and rhetoric. Based on later quotations of his work, he seems to have been rather fond of writing philosophical dialogues.
Heraclides has often been credited with proposing a heliocentric view of the cosmos, but this is not true. Along with some other Greek philosophers, he did propose that the daily movement of the stars could be best accounted for by an Earth which rotated on its own axis once every 24 hours, and according to a later tradition he also suggested that the planets Venus and Mercury revolve around the Sun, but he never suggested that the Earth itself moved around the sun, meaning his understanding was more of a modified geocentric model rather than true heliocentrism.